Human Bone Marrow During the Last Three Months of Intrauterine Life

Abstract

Quantitative histological studies were carried out on the marrow of the ribs from 56 stillborn and newborn children. There is a progressive increase in the quantity of marrow hempopietic tissue throughout the last 3 months of intrauterine life, but no comparable increase in the marrow blood sinuses. Quantitative assessments of the cells in sections suggest that the marrow tissue reached full cellular activity by the 30th intrauterine week and that no increased cellularity occurs or significant change in myeleoerythroid ratio occurs from this time until full term.